


Arrival

by moirae



Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Additional Warnings In Author's Note, Alpha/Beta/Omega Dynamics, Attempt at Humor, Blood, Felix Hugo Fraldarius/Sylvain Jose Gautier - Freeform, Marking, Masochist MC, Mating Cycles/In Heat, Multi, Multiple Pairings, Non-Traditional Alpha/Beta/Omega Dynamics, POV Multiple, Praise Kink, Scents & Smells, lots of kink, seriously
Language: English
Status: In-Progress
Published: 2019-08-30
Updated: 2020-03-27
Packaged: 2020-09-29 23:17:07
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 13,289
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20444210
Author URL: https://archiveofourown.org/users/moirae/pseuds/moirae
Summary: In a twist of fate that is best described as cruel and unusual punishment from the literal goddess of creation herself: Byleth presents as an Omega, in her twentieth year of life.At least the blushing boy-king she teaches is cute.





	1. Relations

**Author's Note:**

> As I put in the tags, this is a non-traditional Omega verse  
Also, I have no one who edits my stuff so sorry for any glaring mistakes.
> 
> Commas are my second lover and it will show.

_ And yet one arrives somehow, _

_ finds himself loosening the hooks of _

_ her dress _

_ in a strange bedroom — _

_ feels the autumn _

_ dropping its silk and linen leaves _

_ about her ankles. _

_\- William Carlos Williams_

**Unknown.1185**

It wasn’t until she began to ascend, her foot planted firmly on the crumbling steeple step, that she felt it. A heady aura, pressing against her throat and pulling her body down, down, deep into the ground. With every step she took, each slower than the other, it coated her, until she was inhaling the intoxicating scent with large, desperate gulps. Her mind, fuzzy, shot with desire, pulled her body up the steps, putting the pieces together quickly, so quickly that her body in it’s dampened state was hopeless to react.

This was the allure of a rutting Alpha. 

Not just any Alpha, her mind teased. She knew this exact scent; wild, earthy, _ coppery. _ He had always smelled like this, even before...before whatever had happened to him, happened. Byleth attempted to stop and shake her head, to clear her mind, and return some semblance of eloquence. Yet she was too far gone, too close to Dimitri, that she merely jerked her head to the side sharply. Soon, she would be an inarticulate mess, mewling and grinding at his feet. Helpless until he did something to check his need.

To halt his rut. 

Physical exertion was what he used when they first met, pushing himself each day past the brink; stringing his hale, Alpha body to it’s seemingly mythical breaking point. Now, however, he either stopped training, or...or, and her mind faltered, with the small, sane part of her trying to halt the train of thought.

But failing.

Failing.

Failing.

_ It’s not enough anymore. _

This was her Omega blood, answering his siren call with a desire to serve, even if it killed her. A Beta, she knew, would be disgusted with the scent, processing it as something vile, akin to the stench of death. While another Alpha would have felt it as a challenge, their blood rising, temper flaring. They would have raced up the steps, blade drawn, not knowing why but _ needing _to fight with Dimitri. Yet she was an Omega, bound to serve an Alpha just as they could only be brought down by the heat of an Omega. 

It was her fools blood that sang in her ears, pumping so loud that she could barely hear her panting breaths. He would be around the corner, she had no doubt of that, waiting for her approach. The moment his aura, his _ need _wrapped around her, he would’ve smelled her response, her answering heat. 

These last few steps were the hardest. Her body was swaying, and she felt her hands, featherlight, brushing against the exposed skin of her neck, her clavicles, her stomach. Everything was too tight, too suffocating, and _ goddess _she was wet. Each brush of her leg was torture, and she struggled on the last step, halting for a moment to squeeze her thighs together, rocking her hips in search of pleasure. 

_ Dimitri… _

She was at a loss. He was there, he had to be there, and in her haze she thought she could see him across the room, sitting in the shadows, but she couldn’t be sure.

_ Dimitri… _

What was in her head and what was actually happening? Was she speaking? Yelling? Whispering? Could he see her? Everything began to blur, and Byleth fell to her knees, her need, his need, all of it too heady, too strong for her to continue on.

She began slowly, dragging her fingers across her sweat-soaked skin and relishing the painful throb of her cunt. It was a pounding heat, begging for attention, and she clenched and released, repeatedly, dragging out her desire. This was going to anger her Alpha. Yet her Omega blood, foolish and mischievous and daring, wanted that anger. It wanted to goad every last bit of lust and rage from his body and to put it all on her, in her.

Her mouth, hanging open with wanton desire, needed something in it. Two fingers, she pumped in and out of her mouth, lavishing them with her tongue. She sucked loudly on them, pulling them out with an audible ‘pop,’ before resting them against her hanging tongue. Leaning back, she grinded down against her heel and - “Ah!” - it felt so, so good. Her hips, rocking like a wave, pushed and pulled her begging cunt across her booted heel, the cool leather a balm on her heat. Finesse long since abandoned, she was trying to deep throat her fingers, which were far too small to give her the burn she desired. Rather, she began to lick her fingers individually, bathing them with her tongue, satisfying her oral fixation. 

Restless, her free hand had entwined itself within the pattern of her stockings, creeping closer and closer to it’s real goal. Deciding to forgo any shred of dignity she might have left, Byleth shoved her hand, ungracefully, quickly, roughly, into her shorts. She gasped at the heat and wetness. Lifting her hips off her foot, she careened forward, ass in the air and cheek pressed against the cool, dirty floor. As always, she lavished her digits, almost obsessively, while she rubbed at her need.

Byleth wanted a tongue there, not her hand. Wanted a hot, slick tongue to caress her slit before delving into her, lapping around her folds and sucking at her clit. A sudden need for pain washed over her, and she bit, cruelly at her fingers, while pinching her clit - “Hah!” Her gasp, mixed so finely with pain and pleasure, was accompanied by the clatter of a carelessly discarded weapon. It seemed she had an attentive audience after all.

It was not the worship of her cunt that she desired, but this, this would do.

Byleth tried to swivel her head around, eyes heavily lidded, seeking him out.

_ Dimitri, are you watching me? _

She had to have said this aloud, for she heard a low, tortured growl near her, but far, too far for her to touch. Her mouth opened, even as her eyes searched, and she sang back for him, moaning louder, still louder with each press against her clit. Her inner walls were tightening, clutching for what wasn’t there.

She paused, briefly, to tug down at her shorts, and that was when she heard it - skin slapping against skin that wasn’t her own. He was pleasuring himself before her, deep within the shadows. Her blood, her Omega blood sang, and any and all tasks forgotten save her pleasure, as her hand pushed back down beneath her shorts and rubbed, desperately, at her core.

_ Please… _

_ Please… _

Byleth was repeating it, to herself or to Dimitri, she didn’t know, but as she continued to rock and rub and bite at her hand, she heard a deep, guttural groan that made her body snap, pulled a cry from her lips, and put stars behind her eyes. 

Falling to the ground, panting, the musty atmosphere rained down onto her body, and she smelled, finally, the crisp night air around her. 

He had been sated, for now.

* * *

**Great Tree Moon.1180**

Manuela’s office, which doubled as the clinic of Garegg Mach, was the least sterile clinic Byleth had ever been in. And she, who had been a mercenary for most of her life, was used to dressing wounds right on the battlefield. Not that she minded, actually - it made the process feel more relaxed and far less the life-changing impact everyone around her was making it out to be. 

Byleth had a crest. 

Which, she assumed, would be the end of that. She was left wondering, naturally, how it had happened. Crests were for nobles, not a child mercenary who developed into a teenage mercenary who then became an adult with the moniker, ‘Ashen Demon.’ Yet, knowing her father, she would never get a straight answer on that. He never lied, her dad, but that meant he rarely spoke candidly with her.

Still, it seemed there was quite a large gap in her home education, especially when it came to crests and what they meant. Abundantly clear, actually, as Manuela dropped three books before her that meant little to Byleth.

_ Understanding the Omega Body _

_ The Culture of A/B/O _

_ Blood Types and You _

“Oh,” Manuela said, rushing over to her desk and pulling out a fourth book. “And my personal favorite-” she laid the new book on top of the pile. “Sex with an Alpha.” 

“Every girl, crest holder or not, dreams of bedding an Alpha at least once,” she informed Byleth, who stared dubiously at the thin book. 

Byleth looked up at Manuela, blinking slowly. “Do they really?”

Manuela’s expression, once so warm and open, turned cold fast. She looked ready to snap a retort before Byleth held up her hand.

“I genuinely have no idea about any of this, and would love any information, incidental or otherwise.”

Like an ever changing summer storm, Manuela was once again her radiant self, fanning her face. “Yes, of course. You are rather expressionless, especially for an Omega, but I suppose that must have something to do with how late you…” she looked down at Byleth’s chest and seemed to change her mind, shaking her head. “Became aware of your crest,” she finished. 

Byleth nodded, leaning forward in the purple velvet chair Manuela had pulled over for her.

“Please, professor, if you could explain…?”

“Professor,” Manuela scoffed, easing into her role of advisor and potential confidant with a certain pride that amused Byleth. “Please, just call me Manuela. You’ve joined the staff here, which makes us equals of a sort.” Byleth nodded again, eager for more information. However, Manuela wasn’t done preening under Byleth’s spotlight, and adjusted her posture several times, crossing and uncrossing her legs, nearly sending Byleth into an impatient tantrum. Could she even do it if she wanted, Byleth wondered, thinking of all the other tantrums she had seen from both children and adults. Tears were almost always needed, and, touching her cheek, she had no memories of ever doing that. 

Finally, Manuela cleared her throat, and presenting a tea pot and cups from who knows where, offered some to Byleth, who accepted, left with little else to do to occupy her running mind. 

“Now,” Manuela started, settling in her chair with her tea, spiked with a mysterious liquid poured from a silver flask, “let’s talk about your blood, shall we?” She smiled teasingly as Byleth, who tried to return the expression. 

“Obviously, you and everyone else around you, has blood.” Images of sliced limbs, festering battle wounds, and slit throats raced in Byleth’s mind - yes, she knew about blood.

“However, you need to understand that not all blood is the same. There are types, you see, determined by, oh-” Manuela yawned, downing the rest of her tea, “by things too boring to go into detail about. Just know that there are three types: A, B, and O. Each of those blood types are also either positive or negative, which we’ll get into later. Now, for those of us without crests, that means little outside of medical work. However, when you have a crest, it seems to impact things quite differently, and instead of having a blood type of A, B, or O, you instead are either an Alpha, Beta, or Omega. Understand so far?” Byleth nodded, pressing her thumbs tightly against her tea cup.

“This changes quite a few things for you dear,” Manuela reached across to pat Byleth’s knee. “This book,” she nodded towards _ The Culture of A/B/O _, “will explain it better, but let me just say, as someone who has worked with many students, of all different crests and blood types, life is never easy for an Omega.”

Byleth felt her stomach clench. What, exactly, did she mean by that?

Was she to grow horns? Lose her legs? Did she only have a year left to live? 

“You have menstruated before, yes?” Her pointed, blunt nature was appreciated. Byleth nodded, foot tapping restlessly. Wouldn’t trouble her at all of those stopped.

“That’s going to get a lot more intense for you.”

Oh. Lovely.

Manuela got up from her chair, walking once more behind her desk.

“Wine?” she called out. Byleth didn’t even have to answer, as before she knew it Manuela was pulling away her tea cup and replacing it with a goblet of wine. 

“This discussion, I feel, calls for a more frank approach,” Manuela explained, resettling in her chair. She had kicked off her heels, and now cuddled into it, uncaring of how high her dress racked up or the wrinkles that were sure to form. 

“I, lovely, non-crestholder that I am, “merely” menstruate once a month, with the usual symptoms. Same with Alpha and Beta women. However, as an Omega, you will have what are called heats during the time you menstruate. So along with the bleeding, and cramps, and whatever else you experience, you now will also have a heightened sex drive, increased body temperature, and give off a scent that will cause any nearby Alphas to go into a rut.”

“A rut?”

Manuela waved her hand dismissively. “Horny.”

“Oh.”

Byleth drank, lightly.

“This isn’t a joke, right?” She asked, looking around the room for any sign that it was.

“No, I’m afraid not. And I haven’t even gotten into the parts about knotting.”

“Knotting?” Byleth was scared to ask.

Manuela tapped the book on top of her pile.

“When an Alpha male has sex, there is a chance, if he has reached a certain point of, let’s say _ euphoria, _ that his co-his _ penis _, will engorge to the point where it won’t slip out, and he will ejaculate, on-and-off, into his partner, for some time.”

“Oh.”

Byleth drank, deep.

She was a virgin.

“What exactly does this have to do with me though?”

Mauela’s voice took on that pitying tone again. “Well, dear, when an Omega goes into heat, and doesn’t find release soon, their heat will intensify, and the lines between consent and rape will blur for them, making them very easy targets for very horrible people. Not saying that an Alpha will be that horrible person, though they very well could be, but just that they are the most likely individuals to be drawn towards you while you are in heat. Betas and other Omegas will smell you, just as Alphas will, although they will process your scent differently. Non-crestholders won’t smell you, but they will notice a glow to your skin, a flush to your cheeks-” Manuela cut herself off, shaking her head. “I’m sorry, as a blood type A they tell me I’m more sensitive to these things, but who knows? I’m sure most of the population here won’t be able to tell when you are.”

This was a lot to wrap her head around. Byleth tried to look at it as objectively as possible - as information she needed to learn to survive. That’s all she was doing - prepping for a new mission. When she was confident that her voice would be strong, she looked up at Manuela, who was refilling her glass.

“So, you’ve told me about heats. What else do I need to know as an Omega?”

“Well, I won’t go over it too much, since you’ll be borrowing these books, but Omegas tend to be more..._ sensitive.” _She studied Byleth’s face, which she knew must have looked as blank as it always did. As unnerving and unresponsive to her thoughts and stimulus as it always has been. “Small-boned as well, though you don’t seem to have that trait either. You, my dear, appear to be a medical mystery. For your sanity, I suggest you avoid Hannenman,” she finished dryly.

Byleth shifted in her chair, knowing what she wanted to ask, but unsure of how to go about it.

“So, these _ heats _, and with how much they impact Alphas…”

Manuela hummed to herself, freely drinking from the bottle of wine now. 

“Yes, and now you understand my initial surprise when Rhea allowed you to instruct the Blue Lions.” She held up two fingers as she drank.

“Two,” Manuela clarified, wiping her mouth on her sleeve. “Blue Lions has two Alphas in their class, and, to be frank, they are the most troublesome of all the Alphas in the monastery. I personally would have put you in Golden Deer.” 

“Troublesome?”

“Oh, one of them will hardly give you any trouble, he’s a very polite, very..._ strapping _young man. It’s the people he trains with that end up hurting - poor thing doesn’t know his own strength. While the other-” Manuela made a sour face. “I’ve had too many girls in my clinic crying over him, telling me how they must be dying of a broken heart for they’ve never felt pain like this before. So I tell them, wait until you bring a man back home and have him turn tail as soon as he sees your bed. That’s a real broken heart.”

“Did that,” Byleth cleared her throat. “Did that happen recently?”

“How did you guess?” Manuela replied, waving the now empty wine bottle.

“Anyways, while we’re on the subject of lonely nights-” were they on that topic? Byleth was losing track. “Self-love, that’s the best advice I can give you. In general, and for this situation.”

“Self-love?”

“Yes, of course. Treat yourself to several romantic nights with yourself, in bed. Alone. Per week.”

Byleth nodded - understanding, slightly, but still confused. When she and her father were hired to join larger mercenary groups, occasionally at night she would wake to hear men grunting beneath their furs, pumping a part of themself that Byleth couldn’t see. When she had asked her father about it, he had given her a hasty, ‘let’s talk about this later,’ and taken her to a chapel to be given a rudimentary sexual education from a holy woman. 

She tried to picture herself alone in bed and grunting, pumping just like the men she saw did, but still lacked an understanding of how that would help. For starters, she lacked the proper parts to pump. Although...Byleth glanced down at her breasts.

_ Perhaps..._

“I think it’s time I leave,” Byleth said, standing up abruptly. Manuela waved lazily towards the stack of books on her table. “Don’t forget your homework.”

Picking them up, taking special care to make sure the cursed text, _ Sex with an Alpha _was tucked closest to her body, she left the clinic in a rush that she intended to keep all the way back to her room until a soft, feminine voice stopped her at the foot of the stairs.

“Professor, a moment, please.” 

Rhea, who had done no personal wrong to Byleth, was briefly the victim of an intense, internal hatred and rage that shocked Byleth. Since when did she feel so passionately about anything?

Shocked still, by both Rhea and her new, bubbling emotions, she was startled when the Archbishop stood before her, with a calm smile and carefully perfumed skin. 

She looked at Byleth, not unkindly, and tucked a stray bit of hair behind her ears. Her fingers, cool to the touch, grazed against her cheek briefly before Rhea pulled them away. 

“Never forget that there can be strength in submission. In my years as Archbishop, I have tried my best to dispel the horrific rumors that follow Omegas, but no matter who I become, the world will always take the word of an Alpha over an Omega.”

Horrific rumors? That definitely intrigued her, but more than that-

“Then you’re also…?”

Rhea smiled at her, eyes twinkling, and held a finger to her lips. 

“Enjoy your life here, professor. As our first Omega instructor, we are expecting great things from you.”

Byleth felt a curious lump form in her throat, like undigested food, and tried, valiantly, to swallow it back down. Her eyes, blinking rapidly from her effort, began to feel wet. Curious. Most curious.

Her chest felt tight, and she was awash with a feeling of shame. 

What is this?

“I-I will be leaving now.”

Rhea continued to smile at her, with just a hint of something sharp, something unnatural in her eyes.

“Of course. Be careful, professor.”

Byleth nearly tripped over herself as she turned away, and going down the steps was no more of an improvement. She didn’t understand anything that her body was doing, the tightness of her chest, the heat of her face, the lump that still bobbed in her throat. Running back to her room, she slammed her door, tossed her books haphazardly on the floor, and walked over to her dresser. Rummaging in her drawers she found it, a small hand mirror that had been a gift from a merchant she had saved. Holding it up to her face, she gasped, nearly dropping it to the ground. Her eyes, normally so blank, were wide and wet with unshed tears. A flush, not entirely unbecoming, she thought, covered her cheeks, and her mouth was turned down into a pout. She swallowed thickly, the lodge in her throat finally removed, and watched as a single tear, her first tear, ran down her face.

This, she realized, is what it meant to be an Omega. 

* * *

**Harpstring Moon.1180**

“Dimitri, are you watching me?”

“O-of course, professor! My apologies.”

He had been like this, Byleth thought, distressed, ever since she began to teach the Blue Lions. Transitioning from the easy, selfish life of a mercenary, to that of a teacher who had to care, and plan, and explain was rough, to say the least, but she had thought she was doing a good enough job. They had won their mock battle, each student was beginning to find their skill focus with her help, and overall seemed to be improving in her presence.

All, save one. 

The cornerstone of her lessons was the individual instruction she gave each student. Speaking to them as a group still made her nervous, unused to so many eyes drilled on her for instruction. However, many times in her life had she helped out a younger merc with swordplay, or taught them survival skills like fishing or tracking, and if she was going to be any good at this, she needed to teach in a way that felt good to _ her. _

Sighing, Byleth watched as once again Dimitri developed a sudden interest in the wood paneling above her head just as she dropped into the lancer stance. The _ proper _stance that a lance user should have, and not the brutal way Dimitri wielded his once the battle began. It left him open for far too many attacks, and took away most of the advantages that lance users had on the field over sword and axe wielders. 

“If you’d like,” she offered, righting herself. “You could get into position and I could adjust your body as needed.”

“Absolutely not!” Dimitri shocked her with how loud his response was, and she winced, along with the front row of students who she noticed were also giggling silently. 

“I-I-what I mean is that-” Grunting, Dimitri pinched the bridge of his nose, and exhaled loudly. When he looked up, his eyes were clear, and, Byleth noticed for the first time, somehow, a beautiful, crisp blue. 

“One more time if you could, professor. I promise.”

So she did, dropping down with the practice lance she had brought into the classroom for this exact lesson, and watched, as Dimitri mimicked her perfectly, not a hint of redness on his face, eyes locked on her stance.

Once she was confident he got it, she broke form, leaning over to clasp his shoulder.

“Good! Just like that, Dimitri.”

A wave of pink, washing over his face starting from his neck, covered Dimitri and he backed away from her touch, making an inarticulate noise. 

“Thank-you, professor!” He stuttered out, bowing; which was a little too formal for their setting, but she let him do what he needed. This was, after all, huge progress for them. “Now if that will be all.” He didn’t let her respond as he left, talking long, hurried strides back to his seat. 

_ Maybe he doesn’t like women, _Byleth thought, watching as he continued to avoid her gaze from his spot. Annette and Mercedes were now openly laughing in the front row, though by no means was it a cruel laugh. Still, she felt bad for the clearly embarrassed house leader, and used the opportunity to dismiss class early, using their excellent progress as an excuse. 

To no one’s surprise, Dimitri was first to leave, with Dedue hot on his heels. 

The others took their time, giving Byleth their gratitude and cheering at the half-day, all thoughts of a flushed Dimitri pushed from their minds (she hoped).

Soon only two students remained, sitting in silence at a table far in the back corner.

It had been a few weeks since meeting everyone, and she memorized all their names and basic information. 

These two, in particular, she knew about very well.

Felix, she had no qualms with approaching, but Sylvain, who had an aisle seat and was staring intently at her, was on a personal ‘ do not approach more than necessary’ list she had developed after her first day. 

He was an Alpha.

No doubt, Byleth assumed, the Alpha Manuela mentioned earlier that broke so many girl’s hearts.

The blood status of her students with crests was considered private medical information, which she didn’t have access too. And, unfortunately, she hadn’t developed her Omega senses to the point where she could pick up on who was what.

Sylvain’s status was only known to her because he simply _ exuded _it. It was a no brainer, something that anyone, crest or no crest, would be able to pick up on.

Which made him extremely dangerous for her.

He knew how to play the game of their bloodlines, but it was all still so new to her.

And the last thing she needed was to get caught up in some Alpha’s power trip.

Still, she was his teacher, and she couldn’t let him know that she was weary of him.

Approaching with the intent to send them on their way, she was shocked when Sylvain spoke up first in his usual, carefree tone.

“How are you adjusting to life here?”

It was an innocent enough question.

And a key to developing a cohesive unit was good communication. It wouldn’t hurt to open up just a little to her students, even if it was Sylvain...right?

“I’m trying my best,” Byleth admitted, “but I’m still unsure of myself. As you know, this was a surprise position for me, and I want to do right by all of you.” 

“Professor, you are simply divine. Nothing to worry about at all.” Sylvain was positively glowing as he looked up at her, smirking. His legs were spread wide beneath the table, while above he leaned against his elbows, chin tucked in one of his hands. The epitome of masculine casualness. Beside him sat Felix, arms and legs crossed tightly, his fingers drumming against his arms as his feet tapped restlessly. “What?” he snapped, when she caught his predatory gaze. His eyes were clear and sharp as they looked her over once before giving her a look that said more words than she would ever hear out of his mouth. All of them, disapproving.

Nothing to worry about, huh? 

“Ignore my friend,” Sylvain cut in, placing a large hand between their locked gaze. Byleth moved her attention back to the Alpha lothario, who she realized, perhaps belatedly, was a predator just the same as his friend, though clearly cut from a different cloth. His eyes were no less assessing at they roamed her body, with the same intent to disarm her, though clearly he had a different reason for doing so, and definitely desired a very different reaction from her, as he trailed his gaze back to her face slowly, torturously slow, his eyes a molten gold that began to make her body feel heavy. Almost, like she needed to sit down. Perhaps in that empty chair between Sylvain’s heat and Felix’s frost... 

“Enough.” The steel in Felix’s hushed voice sent a grounding chill down Byleth’s spine, and Sylvain’s as well, for the red-head stood up quickly and bowed, rather sloppily, in apology. 

“Apologies, professor. For a moment, you seemed like a peer. It won’t happen again.” Yet he flipped his head up at the last moment and winked at her. 

_ Unless you want it to. _

Balking, Byleth continued to stare like a beached fish at her student, whose posture had fallen back into it’s relaxed stance. Her eyes pricked, _ pricked, _with humiliated tears, a new emotion, a completely foreign sensation that shocked her into continued silence. While, most unpleasantly, she felt a throb of heat that accompanied her embarrassment. 

Something changed then, abruptly, with Sylvain, who uncrossed his hands from behind his head and reached out for her arm.

“Hey, professor, are you sure you don’t want to-”

“Move!” Like a cool wind, Felix’s demand shook Byleth free from her trance, and she looked over her two students with renewed clarity. 

“Class is over,” she replied firmly to Sylvain, who was now grinning sheepishly at his fuming friend. “You are dismissed.” 

“I got it, I got it,” Sylvain drawled, waving a hand as if to erase what had just happened. “Later professor.” 

“Don’t let them do that to you,” Felix snapped on his way past her, carefully avoiding brushing against her body. “Any scraps you give them and they’ll run away with it, like beasts.” 

“Who is the other…?” Byleth wondered aloud, just as Felix mumbled “Omegas…” under his breath, shaking his head. 

\- -

It was still early evening, class had just been released and she hadn’t yet ate supper, but all she could think about was sleep. Heading back to her room, in a half-dead, absent-minded state, she closed her eyes once she entered.

Breathing.

In.

Out.

In.

Out.

Opening them, she eyed her bed, stripping slowly, and moved between the covers, enjoying the contrast of the rough, hand-spun quilt against her skin.

Well.

Byleth picked up one of her heavy breasts and squeezed it, playfully, trying to mimic the pumping action she remembered.

Might as well turn this into a self-love date night.

She snorted, rolling her eyes.

As if that was going to make any difference in her life.

\- -

It only takes her a week to discover, rather pleasantly, that self-love is indeed a _ crucial _ part of life. 

Privacy, which she once scoffed at as an unnecessary luxury, had quickly become an essential for her as she explored her body with a freedom she never had. As soon as her work for the day was over, she would rush back to the confines of her room and quickly strip. Sometimes she would spend hours just feeling her breasts, squeezing and contouring them, pinching at her nipples, fascinated, when they pebbled under her touch. She had, and this secretly made her feel quite prideful, noticed now that her breasts were quite large comparatively. And her thighs. And her hips. And well...a lot of things. She would be lying if she said it didn’t put a new strut in her step, though she hoped it went unnoticed. It did make her wonder, however, what it would feel like to touch breasts that were smaller. What did they look like without the confines of a brassiere? Did they also lay against their chest like perfect raindrops? 

Oh, and don’t get her started on the male anatomy. Just what were _ they _hiding? It was a frequent daydream of hers, and one that she indulged this morning as she grinded against her pillow. 

Her pillow.

Her blessed, beloved pillow which she once just used, pitifully, as a place to rest her head.

It was so, _ so _ much more. 

Still, her room was beginning to feel quite stuffy from all her recent activity, and that same early, mid-week morning, she threw open her door and window, airing it out once she had finished and dressed. Initially, she hadn’t seen the problem with this. Yes, she had noticed Dimitri walking past her room several times now, always sure to keep a wide breadth, glancing at it when he thought she wasn’t paying attention. Still, she chalked it up to a general oddity, nothing to concern herself with. He was quite shy with her, and perhaps he just had a question he was too nervous to ask her. Besides, these papers weren’t going to grade themselves, and she couldn’t waste any more of her time with indulgent worries and activities.

It wasn’t until a familiar voice cooed at her from her doorway, that she realized she indeed had once again made a cultural faux pas. 

“Hey there professor,” Sylvain was leaning against her door frame, long legs stretched out to the other side, effectively boxing her in. 

“Sylvain.” Byleth gave him the briefest of glances from her paperwork, but it was enough to make him smile. 

“Mind if I come in?” 

“I do, actually. I’m airing it out, not letting things in.” He inhaled deeply at that, groaning in pleasure. “I can smell why,” he replied, just as Byleth felt her stomach clench in a sensation she now recognized as desire. “Wouldn’t want to keep this all to yourself now, would you?”

“All to myself…?” Even if she was falling into his trap, what he was saying made her curious, and he was the first person to approach her all morning. If she was making a mistake, she wanted to know what exactly it was.

Sylvain began to move further into her room, but she shook her head, remembering Felix’s advice, and pointed at the doorway. “Explain first,” she said, “Please.” 

He chuckled, returning to his spot, and shrugged. “Just figured you wouldn’t want me saying this out in the open.”

Byleth narrowed her eyes. “Whisper it.”

“You’ll have to come closer then.”

Stubbornly, she scooted her chair closer to him by just a hair. 

“Everyone with a crest can smell what you’ve been doing in here, _ Byleth _.” 

The pointed use of her name didn’t go unnoticed. Pulling back from him sharply, she stared up at Sylvain, whose expression had darkened. “I knew we were compatible,” his voice was husky, pitched low. “As a student and teacher, of course.” Suddenly he seemed to tower over her, and his smirk, pointed, predatory, spoke clearly of who the teacher would be. 

“You’re lying,” she said, trying to push past her embarrassment. Thankful, for once, for her stony expression which she knew wouldn’t betray her inner turmoil. 

Sylvain shook his head. “I would never want there to be lies between us. In fact, I don’t want anything to be between** _ us_ **!” He yelped the last word, confusing Byleth, until she noticed the large, calloused hand gripping his shoulder. 

“Hello professor. Sylvain.” Dimitri’s voice was smooth, but she saw an aggression in his sky blue eyes that was new. “Enjoying the spring air?” 

“I _ was,” _Sylvain retorted, putting his hand over Dimitri’s wrist. “Quite the grip you’ve got, your highness. Might want to work on that friendly pat before you actually manage to touch a woman.” It was said with a friendly enough tone, but something was clearly transpiring between the two childhood friends as they now glared at each other.

Which, to Byleth, definitely seemed like a ‘them’ problem and not a ‘her’ problem. Meaning, it didn’t have to take place on her doorstep. Before she could intervene however, a pitched, aggressive voice yelled across the dormitories, “You disgust me!”

Ingrid.

Beautiful, perfectly timed Ingrid.

Sylvain immediately jumped to attention and looked at Byleth. “Sorry professor, _ gottagonow.” _He sprang away from Dimitri, shrugging off his hand, and began to run. Dimitri turned to gaze at Byleth, unperturbed. 

“Are you okay?” He asked, as Ingrid’s furious footfalls continued to approach. His eyes, still clouded with a temper that boiled just beneath his cool surface, pierced through her. There would be no lying to this man, she realized. Not ever. 

Ingrid arrived, red-faced and slightly out of breath. 

“Did you see where Sylvain ran off too? He’s been behaving so-”

“Are you okay?” Dimitri repeated, interrupting Ingrid, in an authoritative tone Byleth hadn’t known he was capable of. Clearly he wasn’t going to let go of it until she answered. Byleth nodded, numb, overwhelmed and exhausted quite suddenly with emotions she wasn’t used to feeling. Oh, and aroused. She was definitely aroused. Because this authoritative Dimitri, who was staring so intensely at her, was doing something, was making her feel things that no one else ever had before.

Well - her gaze quickly flicked to her pillow - except for him.

Dimitri, who had been staring at her so intently, happened to follow the quick snap of her eyes, and suddenly flushed a furious crimson, back to the blushing boy-king she was more familiar with. Confused, horrified, Byleth looked more closely at her bed. Please tell her that crest holders weren’t capable of smelling the objects that got her off. That would be too much, that would be…

Peeking out from behind her pillow, was a frequently read text.

_ Sex with an Alpha. _

_ AHHHHHHHHHHHH! _

“Dimitri,” Byleth said calmly, standing up from her chair, hands folded before her.

_ AHHHHHHHHHHHHHHHHHHH! _

“I think you should leave now.”

** _AHHHHHHHHHHHH!_ **

“Y-yes! Professor! Yes!” Nearly tripping over his cloak, which had wrapped around his upper body tightly from the speed with which he turned, he fumbled away, taking with him any dignity that might have existed in their working relationship. 

“He can be so odd sometimes…” Ingrid mumbled, jolting when she realized Byleth was still there. “Oh, professor, I’m sorry you had to hear that. I don’t mean to speak ill of our future king, but…”

“You grew up together,” Byleth completed, wondering, idly, where she could buy wine in the monastery.

She had never felt more connected to Manuela than in this moment. 

“Is there anything I can do for you?”

“Oh! Hm? What was that?”

“I just mean that, I know our class can be difficult. Well, actually, I should say that I know of three individuals in our class who make things rather hard. I’m always an empathetic ear if you need one, professor. I’ve had years of experience with them.”

The two shared a mutual look of understanding, with Byleth attempting to smile. 

“Huh,” Ingrid said, tilting her head. “Was that almost a smile?”

“I’m trying.”

“I think you’ll get there very soon, professor.”

“That’s kind of you to say, Ingrid. At least I’ll be able to grasp that concept soon. I’m still mystified by all of-” Byleth gestured vaguely at their bodies, “_ this.” _

“That’s right, you just recently came into your crest, didn’t you? And as an Omega too.” Ingrid winced at that, before quickly trying to apologize again. Shaking her head, Byleth spoke up first.

“It’s exhausting,” Byleth admitted, and Ingrid nodded sympathetically. “I can’t even open my window without breaking a social norm.”

“It is tough, professor, even as someone who was raised within it. Just know that in the Blue Lions, we understand where you’re coming from, and our respect for you is unwavering, including Sylvain.” She bowed, and Byleth crossed over to her student, hands held up in platitude. 

“Ingrid, please, that isn’t-”

“You are a more than capable commander, and I look forward to learning from you.” She smiled at Byleth, effectively muting her.

“Now, if you’ll excuse me, I still need to have a word with Sylvain about his behavior. See you tomorrow, professor.”

Byleth watched as she left, feeling very much uplifted and calm. It was, in an odd way, similar to how Felix made her feel. Both of them were certainly a breath of fresh air on her mind, though one was undoubtedly colder than the other.

Taking the opportunity to peek around the courtyard, she expected to see the usual groups, gossiping and playing. 

Today, however, it was empty. 

Something had scared them off.

Rather suddenly, her head throbbed, her eyes burned, and Byleth shut her door and window with far more force than necessary, positive that it echoed. 

Oh, the wonderful world of Omega mood swings.

All she had wanted was some damnable fresh air in her room. Yet nothing was simple for her anymore, was it? Now she was feeling so many things that didn’t make sense to her. 

Anger. Sadness. Lust. 

Before, she had two states: awake, asleep.

Now...now it was all becoming so complicated, so overwhelming. And all of that on top of, on top of…

Byleth reached across the room, grabbed her pillow, and screamed into it. 

It helped, honestly, and she let out what must be her bodies poor imitation of a laugh, for it sounded course and wet to her ears. Still, it was _ her _laugh, and she screamed again in her pillow, just for a chance to hear herself laugh again after.

Everything was just so ridiculous now. 

Alphas, and Betas, and Omegas. 

She screamed, again. It felt incredible!

Back and forth, back and forth.

She screamed.

She laughed.

And, at some point, she cried for a little bit too.

These were all new expressions, new feelings for her, and she was reveling in them all.

Sometime later she picked herself off the ground and walked to the Sauna, thankful that she didn’t run into any of her students.

_ Will this draw in any Alphas, _she wondered, with no small measure of sarcasm as she dipped into the steaming waters, naked. 

Which was supposed to be a completely innocent thought, but now she was thinking about if it _ did _attract one, and she would be lying if she didn’t have a person in mind.

Or two.

Maybe a possible third as she began to daydream.

Oh! Well, there was a fourth one.

It seemed she had no boundaries anymore.

Sighing, she got up from the bath far earlier than she intended and dressed, quickly, shuffling back to her room. 

Like approaching a task one had become beyond used to, she striped once more, grabbed Pillow, and tried to sort out her thoughts.

It turns out, she could indeed narrow down her desires to the person who most interested her.

Though her choice was...interesting, and impossible at best.

Flopping down on her bed, she rested her blazing cheek against the mattress, just listening to her panting breath until sleep began to overtake her.

She could do this, Byleth thought confidently, snuggling further into her bed.

She would handle these new developments and come out the better for it.

The Ashen Demon, that’s what they call her.

And that’s what she would live up to.

\- -

The next morning she awoke, her sheets and nightgown coated in blood.

She couldn’t handle this.

She wouldn’t handle this.

Ugh.

And, just when she thought it couldn’t get any worse, a girl’s voice, that she may or may not have imagined, said:

“You are disgusting. I have had my eyes and ears shut for a week now.”

Double ugh.


	2. Emerge

**Summary for the Chapter:**

> Heats continue and Byleth learns more about this A/B/O world

**Notes for the Chapter:**

> Sorry for the delay! My life had several upheavals shortly after posting this story, but I never forgot about it! I have several other stories and one shots I need to put up as well. Without further ado - also, please notice I added two tags :)

_ Rain is the most precious boon to the unmarked Omega, and a sign that the mother Goddess has not completely forgone us. All the scents of a dampened community, no matter how large or small, rural or bustling it may be, are enough to mask the potentancy of a heat to something tolerable for an Alpha. Maintain your hygiene and gird yourself against lust - your natural scent will be a worry for another day. _

_\- Understanding the Omega Body_

There is a splattering of rain this morning. Hardly enough to evoke his attention; he was a man of Faerghus, and had trained through worse. Grip stance had to be adjusted, his footwork slower, but his movements became more economic, focusing on strength over speed. 

It was a brutal dance, one that spoke of survival. He had to be in the right mindset for it; to feel the chill of the air, the sharp inhales of his breath, the smooth slide of his heels.

Unfortunately, he was not the only one who didn't mind the rain.

It's moments like this, when Felix is frequently and unbiddeningly reminded of the one rule of life browbeat into him as a child: Every Beta has an Alpha. 

The Holy Kingdom of Faerghus _ adores _Betas. Inborn knights, they have a destiny of unwavering loyalty towards an Alpha, who is typically assigned to them at birth. Betas are the shield to the sword of an Alpha, and guard them against threats of all kinds, including the debilitating presence of an Omega.

However, Felix refused to be a shield. He wouldn't be Glenn - strapped to the arm of some shoddy noble and left broken on the field.

Felix was a sword.

Terribly, he found an Alpha that was stupid enough to _ want _ a sword as his shield. It didn't matter that Felix spit at his heels and would rather fall upon his weapon than call himself that man's Beta - _ he _knew, the Alpha knew, that as soon as he asked, just the one time, for Felix to watch over him as his Beta, that he would.

It had taken Felix a painful amount of time to pull himself away from his birth Alpha, the Boar Prince, and just when he thought he finally had what no Beta did - freedom - Sylvain approached him just before they began classes at the Monastery, telling him (because Alphas don't _ ask, _it's one of their "charms"), to be his Beta.

Felix refused, and he tried to cover the eager beating of his heart, the comfort that service and loyalty and responsibility brought him (much to his disgust), by threatening Sylvain. The idiot just laughed, and explained that Ingrid was transitioning over to be Dimitri's Beta, conveniently leaving out that Felix used to have that role, which meant he needed a new Beta, and he wanted Felix.

It was that simple word, _ want, _that sealed Felix's damned fate. A shadow must have fallen over his face then, some trace of his inner thoughts because Sylvain patted his shoulder, giving Felix a thumbs up.

"We're going to have a great time. You'll love watching my back, trust me."

It was already one month into their arrangement, and Felix hated it.

He should have been the only person training in the arena this cold, wet morning. Yet occupying a corner was Sylvain, surrounded by a group of three girls who were bundled up for winter. Southerners had been the object of Sylvain's fickle but passionate attention since day one, though Felix knew not why. They seemed weak and unweathered to him - more spoiled than the nobles he grew up with.

Sylvain himself occupied the corner, leaning against the wall with his arms crossed and sleeves rolled up. Conveniently, he also had the only spot with a touch of cover, and Felix knew his vision didn't deceive him when he noticed a hint of merriment in his eyes each time a girl shivered.

He found it hard to believe that none of the girls had noticed, but even if they did, he doubted they would say anything. All three of them were notorious noble hunters, and Felix found he could spare them no pity as they attempted to trap Sylvain. He was fire disguised as light, and would burn them all as soon as they touched.

Felix snorted, breaking himself from his revere. He had spent too long reading that damnable book Ashe had forced on him, and lines from the novel were bleeding into his thoughts.

What _ mattered _was clearing out the training yard so he could practice.

Rather than sheath his sword, Felix held it out in an aggressive stance and stalked over to the happy quad. Sylvain noticed his approach and smirked; almost, _ almost _halting him. If the bastard had some scheme up his sleeve, Felix would play no part in it. All he had to do was scare off the women anyways. They would scatter like startled cats the moment he spoke, Felix knew that for certain, though Sylvain would remain as unperturbed as before, as stupidly confident as a dog.

Felix _ hated _dogs.

"I, um, I have a question, Sylvain." It was the shortest of the girls, and she had a quiver in her voice that put Felix on edge. Though crestless, he could sense that her blood type was O. The other two were type B, easily recognizable by the way they politely allowed their friend to speak, and stared reverently at Sylvain under lowered lashes.

The hierarchy existed even among the crestless, though he doubted they could see it.

Pathetic.

Sylvain leaned down to be eye level with the girl, and Felix could see the shaking of her knees from behind. Sylvain was going to eat the woman up as a snack, and the fool would enjoy every bit of pain it brought her.

"So is it true?" She continued, breaking off with a nervous giggle. "Do Alpha men, y'know…" Felix couldn't hear what she said next, but it put a broad smile on Sylvain's face and made the other two girls hit their friend playfully on the back. "You're so _ bad," _ he heard one of them whisper, and it stopped Felix in his tracks. 

This was a conversation he did not want to walk into.

Sylvain glanced up at Felix, possessing an uncanny ability to detect his discomfort, and winked. The women, too enraptured at what Sylvain was about to say, didn't even bother to turn and look.

Putting away his sword, Felix crossed his arms and observed for now, telling himself that he was simply waiting for the right time to scare off the nobles, _ not _that he was making sure this line of questioning wouldn't set off Sylvain in a rut.

"You're talking about knotting, right?" Sylvain confirmed in an exaggerated whisper. The girls nodded, eager for forbidden knowledge. "Ladies, ladies...that's so _ knotty _of you to ask." The four of them broke into laughter, with Sylvain pushing off the wall and trying to hug all three women to his chest.

Felix was going to be sick.

The fact that even for a moment he had been worried was pathetic. He was no simpering Beta following the lead of his Alpha, like a bitch bred hunting hound hanging on the command of his owner. Rolling his eyes, Felix turned to walk away as the giggles turned into soft gasps, and Sylvain's ever wandering hands trailed down from shoulders to trace bodices and waists. 

Boar Prince be damned, he would resume his training in the Knight's Hall, though he loathed the atmosphere.

Yet before him, Felix discovered, was an even larger problem. Sneaking around the scent of rain was a touch of musk. It was sweet and feminine, dancing around the raindrops and working its way towards the Arena.

It was the scent of their Professor, heightened with the bane of all Omegas and Betas - _ heat. _It was the natural smell of her slick and blood mixing, dripping from her body and calling out to everyone, Alphas in particular, that she was unmarked, but fertile. Waiting, wanting to be claimed. As far as what the woman herself desired, Felix knew nor cared much at all. Neither, Felix thought, would Sylvain, who stilled his minstrations based on the protests of the women.

Pinching the bridge of his nose, grateful for the rain dampening his ignorant Professor's heat, Felix walked back over to the young lovers and snapped once, loud even with gloves. 

"Leave, now."

They listened, scurrying away quickly, but the petite woman caught his eye as she left, a curious look in her glance. Felix scowled at her, and she blushed.

Crest or no crest, with O in your blood you were doomed in the world, Felix thought, rolling his eyes.

"Disappointed in me?" Sylvain asked, once the doors slammed shut.

Felix snorted, crossing his arms and throwing a glare towards Sylvain that quaked men twice his size. "You're assuming I'm ever anything else."

Sylvain hummed, unbothered, eyes growing darker. Felix shifted, the gagging scent of Sylvain's rut increasing. Byleth had long since moved away, her scent trailing behind, but that didn't seem to put Sylvain at ease. A thick piece of hair fell from his top knot, curling against the side of his face, the ends tickling the corner of his mouth. Before Felix could brush it aside, Sylvain’s hand was already there, tucking it back behind his ear, gloved fingers brushing against his cheek. Felix flushed, determined to look anywhere but _ him. _ Sylvain touched so easily, bridged the physical gap between individuals with such nonchalance that was foreign to Felix, who consciously distanced himself from others. _ How _ he did it, and _ why _boggled his mind, frying his thoughts and instead making his emotions and instincts take over. 

The Alpha before him shuffled, and Felix subconsciously followed the movement, catching him in the act of adjusting himself through his pants. Flicking his eyes up and away quickly, heat further staining his cheeks, Felix gripped the hilt of his sword.

"Disgusting…" he hissed under his breath. A loud clap of thunder, and the once gentle rain turned into a torrent, matting Felix's hair to his face. His bun was starting to weigh heavily against his head, irritating him further. 

Sylvain took a step towards him, bile working up Felix's throat at the approach of him and his heat. Felix avoided eye contact when he could, with everyone, but Sylvain was an alpha, a _ strong _alpha, and Felix could not help the subservient way his eyes glanced up towards his - from here, Felix could almost see little flecks of green in Sylvain’s eyes, while his he knew were a true brown. 

"Control yourself!" Felix snapped, moving to pinch his nose. Sylvain slapped his hand away, looking so rarely intense, bearing his gaze down onto Felix.

"You're the one who needs to calm down Felix. Do I scare you?"

"You smell disgusting," he countered, clinically looking Sylvain over - anything to avoid his eyes. While Sylvain had adjusted himself, the hard line of his cock could still be seen. 

"Curious?" Sylvain asked, his voice teasing. "We could compare like when we were kids. I've grown a lot since then, you know."

Felix looked up sharply. 

"No. Besides, I'm just as tempted to cut it off now as I was back then."

"Now, now-" Sylvain stretched his arms behind his head, water trailing down from his upturned face and collecting at his throat. "No need to be jealous."

Felix was tempted to hit his friend for that, but stopped, the retreating, sickening scent of Sylvain's rut still lingering. When an Alpha was in heat, it was dangerous for even a Beta to touch them. 

"You know," Sylvain began, looking down at Felix. "It only smells so bad because you're nervous."

Rolling his eyes, Felix huffed a response.

"You wish, idiot."

Again, the ridiculous humming as an answer.

"I'm going back to training," Felix snapped in tandem with a boom of thunder. Twisting around smoothly, even with the water flooding the floor, he pulled out his sword and returned to his stance, taking a deep inhale.

"Take care not to cut yourself," a voice whispered in his ear, and Felix sent a sharp elbow back, catching Sylvain in the gut. Grunting, he patted Felix's shoulder.s

"Annoying…" Felix muttered, trying his best to reset his mind. Taking a few extra breaths, he began to find his inner peace and center before _ again _Sylvain cut into his thoughts.

"Thanks for watching over me," Sylvain called out, waving his hand lazily. "I'm going to go chase down my lovelies."

"I wasn't protecting you!" Felix snapped, bringing his sword down sharply, no longer concerned for proper stance or mindset.

Sylvain's answering chuckle haunted Felix through the rest of his training.

* * *

Mercenaries didn't panic. They couldn't afford to. Jeralt hadn't bothered teaching Byleth this core tenant - she had been unperturbed since birth. Currently, as she strode about her room, thighs slick with blood, heart hammering, she realized for the first time that this must be panic, and she could definitely see how it would kill a soldier. The mysterious voice that woke her wasn’t responding to her panic thoughts, and Byleth easily forgot about it as her heat continued. 

_ You need to relax. _

Yet the more she repeated the mantra to herself, the faster her heart beat, the more panicked and hyper aware she became. Her body was clenching, tight with cramps, and it took all her effort not to walk double overed, clutching at a wound no one could see. 

It was illogical, insensible, and she knew it was, but all she wanted to do was give in to herself for a measly moment and cry on the floor, sitting in her own blood and relishing her sad state for as long as she could stand.

_ Why why why? What would that do for her? For the situation? _

Byleth had never had an impulse. 

A desire to act afoul of reason.

She was feeling too much, too soon. It was swallowing her whole and she had no idea how to fight the beast inside her.

_ If you're ever at a loss, run. Move. Don't stand there dumbstruck, waiting for an enemy to cut you down. Move so at least they have to work for the kill. _

Byleth ran across her tiny room and bundled up in a heavy winter cloak that was off season, but would mask her somewhat. Nearly forgetting her shoes, she slipped out the door with such alacrity that she scared the two girls just outside her door, huddling under the cover of her walkway.

It was raining. She had no idea.

For some reason, the look of unease on the girl's faces as they took in Byleth's harried appearance, combined with the gloom of the weather, gave her a perverse satisfaction.

Moving around them, she headed towards the only person she knew who could help her: Manuela.

\----

In a rare stroke of luck, her walk up to the infirmary was met with no resistance. There was still a brief window of time before classes began, and Byleth slipped around the lingering staff as best she could. Dimly she was aware of their small gasps as she passed, of how more than one person tried to grab her shoulder. She hoped Jeralt wasn’t one of them.

She reached Manuela’s office only to find it locked. Of course.

Byleth was just about to slam her head against it when a boy’s sharp voice said, “I don’t know who you are ma’am, but you’re tracking water and blood all over the floors and I just cleaned up.” 

Cyril. Sighing, Byleth tugged down her hood and stared at him. The misery on her face had to have been evident, even considering how limited her facial expressions were. Cyril studied her briefly, opening his mouth to respond before a sharp voice cut him off:

“What’s going on here?”

Authoritative, superior, elegant - Seteth was suddenly behind Cyril and exuding an energy that cleared the room quickly, leaving the three of them alone in the upper wing. Byleth felt a warm trickle of blood race down her leg as he caught her eye, and watched for a reaction from Seteth. His nose twitched, and though he looked no different than usual, it was enough to send Byleth into a spiral of shame. 

Shame. It was so surreal now to feel the toxic emotion tainting her body. She had never felt it before, had never doubted or second guessed herself. When she made a mistake, didn’t fit in, it was what it was and she moved on. Yet now she felt like stewing in it, felt like she wanted to rub the burning feeling all over herself and linger in the doubts and pain it brought her. She found a perverse part of herself enjoying the racing of her heart, the heat of her face, the prickle of tears at her eyes. Panting...panting, yes - she had to be panting. Why wouldn’t she stop? 

Seteth was doing something to her. The longer he stared at her with that _ look, _and exuded that energy, she was feeling more filthy, more diminutive than ever before. 

The sick, perverse part was that she didn’t hate it.

It horrified her.

Byleth took a step back from Seteth, and from Cyril too who was watching her with concern. 

“Are you okay?” She heard him ask. Byleth didn't have the presence of mind to respond. 

Without a word, Seteth reached inside his pocket and pulled out a key ring. Unlocking Manuela’s office, careful not to intrude in Byleth's space, he gestured for her to go inside, who needed no more encouragement. 

“The back cabinet, beside the glass jars. You will find more than enough to help you.” Seteth said as she passed him, his head turned to the side, facing away from her. 

Byleth began to make quick strides towards it.

“Wait!” She halted, digging her fingers into her palm. She wanted to turn and look at him. She wanted to feel that burning shame once more as he looked down on her as if she were a mess only he could handle. 

"Advice for you professor, that was given to me long ago: Don't fight yourself. You can either be your worst enemy, or your closest ally."

She didn’t know what to say to that. How to react. 

“Meet me in my office when you’ve finished cleaning yourself.”

It wasn’t a question. 

Seteth closed the door, and Byleth flexed her hands out, the half moon indents from her fingernails giving her a pleasant rush of pain, grounding her. 

Wait...a _ pleasant rush of pain? _

Byleth pressed her hand against her forehead, groaning. Where had that come from? Since when did she find pain enjoyable? 

A rushing cramp forced her to bend over, the strength of it forcing a gasp from her mouth. She saw small droplets of blood leading from the door to her spot, and dreaded to see the state of her nightgown and cloak once she removed them. With luck, the cabinet would have no only the padding she required, but a new set of clothes and cleaning supplies.

\----

Seteth was a fashionable man. Foppish, she heard a disgruntled student describe him after being given detention from the man. Byleth wondered what he thought of her new outfit as she sat across from him in his office. 

As if reading her mind, he said, “That was an older version of our officer’s academy uniform. We used to require staff to wear them, though that was before Manuela began to work here.” They shared a look, and Byleth relaxed, just a bit in the high back chair he pulled up for her, and she saw him give her the tiniest of smiles. 

Clearing his throat, Seteth tucked his hands under his chin and looked at her critically, smile wiped from his face. “Now, on to business. Have you read any of the texts Manuela provided to you?”

“One of them.”

The look Seteth gave her implied that not only could he guess which one, but also that he didn’t approve. 

“I am assigning you to bed rest today, Professor.” She opened her mouth to protest, but Seteth quickly cut her off. “Your duties as a teacher of the monastery are serious. It is not a job you can hack your way through. It requires a keen mind, and the ability to focus on what is in front of you-” Byleth made a sound of protest and he held up his hands, “as well as ensuring that your students are doing the same. At the moment, you are not in a state that would guarantee that of your class.”

“It is not that I think of you as incapable,” he clarified, sensing her darkening mood. “Rather, your students are young. _ You _are young. It does not take augur to see where this will go if you do not collect yourself.”

“You speak as if something illicit is already happening.” Her voice was pure ice. 

Seteth looked away, conflicted. “Spend today reading your texts, professor. Train yourself to live in our culture, and then you will see what is already there.”

“Why can’t you just tell me?”

“I cannot. That would defeat the purpose of you experiencing it for yourself.”

“You sound like a mercenary,” Byleth replied, thinking of something similar her father had once told her when she had asked him how it felt to watch a man die. He wouldn’t tell her, because that would defeat the gravity of the situation. It would taint the impact it would have on her. 

“I have not always worked at the monastery.” 

Byleth looked at him curiously, though he said no more. They sat in silence for some time, the muffled sound of rain beating against the roof echoing around them. A cool breeze wafted over her, and Byleth looked down at her exposed thighs. She was unused to not having tights or pants on. The white socks that accompanied her skirt only went up to her knee. Byleth tugged on her skirt, trying to get more protection for her skin, when a scent caught her attention. It was clean and light, crisp lemon and bergamot. Ginger chased after the citrus, a spicy twist leaving her feeling sharp and awake and fresh.

"Mmmm," Byleth let out an appreciative moan. "Something smells so good."

"Well, I…" Seteth coughed pointedly and she looked over at him, a light blush on his cheeks. "While I understand your intent was not to- that is to say, you are still ignorant of our culture…" 

Byleth tried to rack her brain for any relevant information as to why he would be acting this way. Had that delicious scent been Seteth? If so, why was he so embarrassed? Granted, Byleth had not been in polite society for long, but everyone enjoyed compliments, she was led to believe. 

"Seteth, why should I have not told you that you smell good?"

"I…" he sighed, leaning back against his desk and folding his arms. "I am not the most appropriate person to answer this question." He seemed to think for a bit, staring at a point above her head before continuing on, slowly. "If you are to teach here successfully, you must be fully aware of your condition."

_ Condition. _He said it like it was something dirty. Byleth stared at Seteth and he startled. 

"Are you frowning? While I am pleased to see an expression on your face, I must admit I did not intend for this. Have I offended you?"

Best not to get into it, at least not now when she wouldn't be able to defend herself, since she apparently didn't even know _ that _anymore.

Byleth shook her head. "No, I am just...frustrated at not having someone else to relate to."

"To relate to, hm?" Seteth sighed, shifting his legs. "While I am hesitant, as you are still something of an unknown to me, my sister is also an Omega, and someone who could assist you in acclimating."

"Flayn? Really?"

"Yes, I suppose it is a shock for you since you're still learning to read others by scent. If I remember correctly, you also have one in your class."

"Hm…" Byleth tilted her head back. It definitely wasn't Sylvain. What was it that Manuela had told her about Omegas? That they were usually small boned?

"Annette?" She speculated, but Seteth shrugged. "I cannot remember her name, only that Flayn has spoken highly of her in the past."

"I'll have to ask her."

"Indeed."

They fell into a comfortable silence, each lost in their own thoughts. Finally, Seteth held out his arm to escort her out of his office. Taking it gently, he turned her towards his door.

"I have decided. Flayn will visit your room tonight to discuss some things with you. I hope it will be of some assistance to you, especially considering what occurs in two days."

Yes, the first serious assignment for her class. Many of her students would be taking their first lives, and it wouldn't do for her to lose focus, or make someone else.

"Thank-you for your help Seteth."

Pulling away from her, he shook his head.

"Thank Flayn tonight, not me."

"I will."

"Good day, professor."

"Good day, Seteth."

As soon as Byleth left, Seteth placed his hands flat upon his desk and inhaled sharply. 

She too, smelled amazing.

* * *

  
  


Byleth spent the rest of the day reading. She felt guilty, hearing the commotion of students outside, discussing their classroom and assignments, that she was not out there and doing her job. Useless was not a feeling Byleth was used to. Day turned to evening as she continued to read. Though she had no proof, Byleth could feel that Dimitri walked past her doorway several times, ever the nervous sentinel. 

The only times she got up was to redress herself. The amount of blood was increased, though according to her texts, the volume was due to her blood now being mixed with something called slick - which her body produced now. It was full of her scent, the slick, and served the sole purpose of attracting Alphas to an unbred Omega. She would produce slick when aroused, sometimes when unaroused, and even as she dreamed. It was considered uncouth of an Omega to have the scent of their slick uncovered, and considering how equal parts aroused and ignorant Byleth had been the past few days, she could now assume what the smell was that had enticed Sylvain earlier. 

The shame she felt at her new knowledge, and the cloud it now put over her first few weeks at the monastery made her blush. Absently, she rubbed her thighs together under her blankets. 

At the exact moment when she got to chapter 13 of _ Understanding the Omega Body _, Byleth heard a polite knock on her door. Opening it cautiously, anticipating already who it was but still on edge considering some of the individuals she met, she nearly jumped back at the excited green eyes that stared at her through the small slit of her door.

“Good evening professor!” 

Exhaling, Byleth opened her door further and stared down at a trio of tiny girls. Flayn, Bernadetta, and Annette all greeted her in their own ways before walking inside her room. Behind them, Mercedes gave a polite wave before turning away once the girls were safely inside. Shutting her door, Byleth felt extremely out of her comfort zone. She had never hosted guests before, much less nobles. 

Yet clearly she had nothing to worry about, as Annette, ever the busybody, was already creating a cozy spot on the ground for all of them to sit. She had pulled out a blanket from her bag, spreading it out, and with nonverbal permission from Byleth, tossed her pillows around too. Quickly, Byleth sat atop her special pillow. 

Once each girl had settled, Annette clapped her hands. 

“Well - should we introduce ourselves?”

“I know everyone,” Byleth interrupted, not unkindly. However, it seemed to deflate Annette some, so she backtracked. “I mean...while I know your faces, a reminder of your names would be great.”

“Weelll, I’m Annette, but you know that professor. Oh, but I’m the president of our club!”

“Club?” Byleth was confused. 

“The Omega Alliance!” Flayn put in excitedly. “When my brother told me of your plight, I knew we had to initiate you into the club.” 

“We’re still new,” Annette continued, “but we’re really enjoying ourselves. See it all happened when Flayn - oh, and that’s Flayn professor - when we ran into each other while I was looking for someone. We instantly knew we were both Omegas , and decided to find out if there was anyone else.”

Byleth, Annette, and Flayn all slide their gaze to Bernadetta who lowered her head into her arms. “You found Bernie alright…” she mumbled, legs shaking. 

“There are actually two more Omegas in the Black Eagles house, but only Bernadetta was willing to join. Or, well, replied to our invitation.”

Bernadetta lifted a hand to cover the side of her face and mouthed to Byleth, “They were following me.”

Byleth coughed, looking away, though a light warmth bloomed in her chest. She was surrounded by people like her, though they hardly knew each other. They had experienced all she had, and more. 

Bernadetta, shy as she was, had to have felt the uncomfortable and uncontrollable arousal a heat brought on. 

Flayn would understand the embarrassment of trying to cover up the smell of your slick.

Annette was aware of how Omegas were looked down on by Betas and Alphas far more than Byleth, as she had lived with it all her life. 

Easing into the group, Byleth asked, “So what do we do in this club?”

Two of the girls beamed, and although Bernie had her face hidden, her legs stopped shaking. They must have been nervous that Byleth was going to laugh them out of her room.

“Well, we usually talk about topics of interest.”

“Such as?”

The room went quiet, with each woman looking at the other until Flayn leaned forward, a conspiratorial look on her face.

"Has anyone else taken notice of Felix's shapely hindquarters?

Byleth raised her hand mutely just as Bernadetta buried her face further into her knees and Annette shrieked a 'yes!'

"His outfit is so very tight and streamlined, though when he turns around," Flayn broke off into a giggle. "There is quite a bump in the road!"

“Oh,” Annette put in, after she was done laughing, ”I’m sure the professor doesn’t want to talk about things like this.” They looked at her, even Bernadetta, and Byleth shook her head.

“No. I...enjoy this.”

The girls cheered and began to rapidly discuss the boys (and, on occasion, girls) they found attractive around the monastery. Even Bernie would give her largely non-verbal input, which the other two were far more adept at reading than Byleth. 

“-he could _ totally _smell me and it was humiliating! Mercie thinks I should give it another try, but I don’t want to push it. They say the smell of slick is offensive to Alphas.”

Startled out her thoughts, Byleth didn’t think before saying, “Actually, it’s the opposite.”

All three girls snapped their heads in her direction, interested that she was finally joining the discussion.

“I mean, I guess. I haven’t been an Omega for long. I, um, presented late.”

“Hm, maybe offensive isn’t the right word,” Annette rectified. “More like, it controls them? Makes them act how they normally wouldn’t? So because of that, they don’t like to smell it unless it’s from their bonded.”

“It’s up to an Omega to act appropriately around an Alpha. An Alpha’s actions are merely reactions to the Omega,” Bernie recited dully. 

“That’s not fair,” Byleth said. 

Suddenly, each other the girls around her looked older than their years as finally Byleth uncovered the core of their club, and why Seteth did not want to be the one to educate Byleth on her new cultural status - life wasn’t good for an Omega. 

Seteth’s overbearing nature towards his sister now made sense. 

“Does everyone believe that?” Byleth asked, thinking back to what Ingrid had told her: _Here in the Blue Lions, we all respect you_

“It’s been the cultural norm for some time now. I mean, no offense professor, but a lot of us were surprised when you got this position. You’re an _ Omega _. We usually don’t get put in positions of power because of how we can make others feel. Well, and to be put in our class especially…”

“Two Alphas,” Byleth finished.

The girls nodded their heads.

“Well, and you know professor, they’re both positive Alphas.”

“Does that mean anything?”

"Well, In Mestizo's _the Law of Attraction, _his research concluded that there is a stronger biological attraction towards those with opposing traits. For example, a negative Omega will attract positive Alphas with their scent and heat more intensely than others. You're obvious to anyone with a crest a negative Omega professor!"

"But is there an actual difference between negative and positive?"

"Well,” Annette continued, the three girls paying rapt attention, “there haven't been many studies, but non-controlled observations have hypothesized that a positive tends to embody the characteristics of their blood sign more strongly than their negative counterparts." 

“And those traits would be?”

“Boorish, overbearing, and perverted!” The girls shared a laugh at what Flayn said, while Byleth racked her brain. She couldn’t think of two people in her class who fit that description. 

“Who is…” Byleth began, just as Annette said, “Oh, but I shouldn’t joke that way about Dimitri.”

Byleth blanched. _ Dimitri _was the other Alpha? How had she missed that?

Her shock must have shown, because Annette giggled behind her hand. 

“You didn’t know, professor? He’s certainly taken a healthy interest in you, though we all politely pretend like we haven’t noticed. Well, everyone except for the usual two suspects.” 

"I feel...bad,” Byleth replied. Well, and aroused. Definitely aroused. Yet she didn’t add that in. She wondered if the other girls also had developed feelings of masochism, and was tumbling the idea around in her head about asking it before Flayn stood up quickly, gather her belongings.

“Goodness, I didn’t realize what time it was! Brother will be beside himself if I don’t return soon.”

“Aww, but we didn’t even get to talk to the professor about heats yet!”

“Next time,” Flayn promised, grasping Byleth’s hands in her own and smiling. “Thank you for joining our club, professor. I do look forward to our next meeting.”

Annette stood up and gathered her belongings too. 

“Omegas never walk alone at night,” she explained to Byleth. “So I’ll walk Flayn back to her room, and Mercie said she would be waiting for me in the library! See you next week professor! Same day and time!” The two girls rushed out, quicker than a gust of wind, the idea of a worried Seteth spurring them on. Byleth’s gaze slid over to Bernie, who was standing awkwardly behind her. 

“Shall I walk you back?” Byleth offered. 

“Oh! I-I mean you don’t have to. Bernie- I mean, I don’t really have anyone waiting for me.”

Byleth tilted her head back.

“Let’s go then.”

It was a quiet and short walk to Bernadetta’s room. The petite student looked around nervously as they walked, staring into shadows and unconsciously getting closer and closer to Byleth. A voice, a familiar voice, spoke inside Byleth’s head - _ I wonder what happened to her? _Startled, Byleth looked down at Bernadetta as they reached her door. 

"Bernadetta, did you say something just now?"

"N-no...wait! Did you hear a voice too?"

Byleth nodded. "I did, and it wasn't the first time either. It's nice to know someone else is hearing her voice." Twisting her hands into her skirt, Bernie avoided her gaze, coughing into her shoulder. "H-her?"

"Yes," Byleth replied slowly. "I heard a young girl's voice. What voice did you hear, Bernadetta?"

"You know what's funny?" Bernadetta asked suddenly, voice high. "That joke I just told. I'm going to go to bed now. Good night!" Racing to her room, Bernadetta slammed her door shut in her nerves. 

That girl can be so odd, Byleth thought, walking back to her room and feeling no more exposed or threatened than she did before she was an Omega. 

_ Definitely, _the mysterious voice in her head agreed. 

**Notes for the Chapter:**

> Preview for next chapter:
> 
> Dimitri's hand shot out quickly, wrapping around her wrist and pulling her in close, slamming the door behind them.  
“Dimitri, I-”  
She was pushed back against the door, Dimitri’s hands moving down to press into her hips. Letting his head fall against the door, she listened as he breathed sharply above her. 
> 
> Once he opened his eyes, she tilted her head up to stare at him.  
“Professor,” his voice was a thinly controlled timbre that held her rapt attention. “You don’t understand what you do to me, do you?”


End file.
